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Keith Donald
2008-04-08 07:56:05 +00:00
parent a359dcc910
commit 83b7932d61
3 changed files with 294 additions and 94 deletions
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spring-webflow-reference/src/defining-flows.xml
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@@ -60,7 +60,7 @@
<sect1 id="essential-flow-elements">
<title>Essential language elements</title>
<sect2 id="flow-element">
<title>The root flow element</title>
<title>flow</title>
<para>
Every flow begins with the following root element:
</para>
@@ -75,11 +75,11 @@
</programlisting>
<para>
All states of the flow are defined within this element.
The first state defined becomes the flow's starting point by default.
The first state defined becomes the flow's starting point.
</para>
</sect2>
<sect2 id="view-state-element">
<title>The view-state element</title>
<title>view-state</title>
<para>
Use the <code>view-state</code> element to define a step of the flow that renders a view:
</para>
@@ -88,11 +88,12 @@
</programlisting>
<para>
By convention, a view-state maps its id to a view template in the directory where the flow is located.
For example, the state above might render from <filename>/WEB-INF/hotels/booking/enterBookingDetails.xhtml</filename>.
For example, the state above might render <filename>/WEB-INF/hotels/booking/enterBookingDetails.xhtml</filename>
if the flow itself was located in the <filename>/WEB-INF/hotels/booking</filename> directory.
</para>
</sect2>
<sect2 id="transition-element">
<title>The transition element</title>
<title>transition</title>
<para>
Use the <code>transition</code> element to handle events that occur within a state:
</para>
@@ -106,7 +107,7 @@
</para>
</sect2>
<sect2 id="end-state-element">
<title>The end-state element</title>
<title>end-state</title>
<para>
Use the <code>end-state</code> element to define a flow outcome:
</para>
@@ -167,10 +168,10 @@
</para>
<para>
Actions are defined using a concise expression language. Spring Web Flow uses the Unified EL by default.
The next few sections will cover the language elements for defining actions.
The next few sections will cover the essential language elements for defining actions.
</para>
<sect2 id="evaluate-element">
<title>The evaluate element</title>
<title>evaluate</title>
<para>
The action element you will use the most often is the <code>evaluate</code> element.
Use the <code>evaluate</code> element to evaluate an expression at a point within your flow.
@@ -199,45 +200,6 @@
</programlisting>
</sect3>
</sect2>
<sect2 id="set-element">
<title>The set element</title>
<para>
Use the set element when you need to assign a flow variable:
</para>
<programlisting language="xml">
&lt;set name="flowScope.selectedHotel" value="hotels.selectedRow" /&gt;
</programlisting>
<para>
Both the name and value attributes are EL expressions.
</para>
<sect3 id="set-element-null">
<title>Assigning a null value</title>
<para>
Use the special <code>null</code> keyword to assign a variable to null:
</para>
<programlisting language="xml">
&lt;set name="flowScope.selectedHotel" value="null" /&gt;
</programlisting>
</sect3>
<sect3 id="set-element-literal">
<title>Assigning a literal value</title>
<para>
Enclose a value within tick marks to assign a literal:
</para>
<programlisting language="xml">
&lt;set name="flowScope.status" value="'Processing Order'" /&gt;
</programlisting>
</sect3>
<sect3 id="set-element-result-type">
<title>Converting a value prior to variable assignment</title>
<para>
Use the <literal>type</literal> attribute to specify a desired value type:
</para>
<programlisting language="xml">
&lt;set name="flowScope.id" value="requestParameters.id" type="long" /&gt;
</programlisting>
</sect3>
</sect2>
<sect2 id="checkpoint-actions">
<title>Checkpoint: flow actions</title>
<para>
@@ -272,7 +234,7 @@
&lt;/flow&gt;
</programlisting>
<para>
This flow now creates Booking object in flow scope when it starts.
This flow now creates a Booking object in flow scope when it starts.
The id of the hotel to book is obtained from a flow input attribute.
</para>
</sect2>
@@ -297,7 +259,7 @@ public interface FlowOutcome {
}
</programlisting>
<sect2 id="input-element">
<title>The input element</title>
<title>input</title>
<para>
Use the input element to declare a flow input attribute:
</para>
@@ -321,7 +283,7 @@ public interface FlowOutcome {
</sect3>
<sect3 id="input-element-value">
<para>
Use the <code>value</code> attribute to denote a specific expression to assign the input value to:
Use the <code>value</code> attribute to specify an expression to assign the input value to:
</para>
<programlisting language="xml">
&lt;input name="hotelId" value="flowScope.myParameterObject.hotelId" /&gt;
@@ -340,7 +302,7 @@ public interface FlowOutcome {
</sect3>
</sect2>
<sect2 id="output-element">
<title>The output element</title>
<title>output</title>
<para>
Use the <code>output</code> element to declare a flow output attribute.
Output attributes are declared within end-states that represent specific flow outcomes.
@@ -407,15 +369,18 @@ public interface FlowOutcome {
These variables are allocated when the flow starts.
Any @Autowired transient references the variable holds are also rewired when the flow resumes.
</para>
<para>
Use the <code>var</code> element to declare a flow variable:
</para>
<programlisting language="xml">
<sect2 id="var-element">
<title>var</title>
<para>
Use the <code>var</code> element to declare a flow variable:
</para>
<programlisting language="xml">
&lt;var name="searchCriteria" class="com.mycompany.myapp.hotels.search.SearchCriteria"/>
</programlisting>
<para>
Make sure your variable's class implements <code>java.io.Serializable</code>, as the instance state is saved between flow requests.
</para>
</programlisting>
<para>
Make sure your variable's class implements <code>java.io.Serializable</code>, as the instance state is saved between flow requests.
</para>
</sect2>
</sect1>
<sect1 id="calling-subflows">
<title>Calling subflows</title>
@@ -423,14 +388,14 @@ public interface FlowOutcome {
A flow may call another flow as a subflow. The flow will wait until the subflow returns, then respond to the subflow outcome.
</para>
<sect2 id="subflow-state-element">
<title>The subflow-state element</title>
<title>subflow-state</title>
<para>
Use the <code>subflow-state</code> element to call another flow as a subflow:
</para>
<programlisting language="xml">
&lt;subflow-state id="addGuest" subflow="createGuest"&gt;
&lt;transition on="guestCreated" to="reviewBooking"&gt;
&lt;evaluate expression="booking.guests.add(guest)"/>
&lt;evaluate expression="booking.guests.add(currentEvent.guest)" /&gt;
&lt;transition /&gt;
&lt;transition on="creationCancelled" to="reviewBooking" /&gt;
&lt;/subfow-state&gt;
@@ -511,37 +476,4 @@ public interface FlowOutcome {
</programlisting>
</sect2>
</sect1>
<sect1 id="simple-event-handlers">
<title>Transitions without target states</title>
<para>
Transitions without targets can also be defined:
</para>
<programlisting language="xml">
&lt;transition on="event"&gt;
&lt;-- Handle event --&gt;
&lt;/transition&gt;
</programlisting>
<para>
Such transitions are event handlers that do not change the state of the flow.
They simply execute their actions and re-render the current view or a subset of the current view.
</para>
<para>
Below is a realistic example of two transitions that handle Ajax events to page through a search results list:
</para>
<programlisting language="xml">
&lt;view-state id="searchResults"&gt;
&lt;transition on="next"&gt;
&lt;evaluate expression="searchCriteria.nextPage()" /&gt;
&lt;render fragments="hotels:resultsTable" /&gt;
&lt;/transition&gt;
&lt;transition on="previous"&gt;
&lt;evaluate expression="searchCriteria.previousPage()" /&gt;
&lt;render fragments="hotels:resultsTable" /&gt;
&lt;/transition&gt;
&lt;/view-state&gt;
</programlisting>
<para>
These transitions change the current data-page, then request re-rendering of the hotels table fragment.
</para>
</sect1>
</chapter>